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<h1 id="一、-shell-函数"><a href="#一、-shell-函数" class="headerlink" title="一、 shell 函数"></a><font size=3>一、 shell 函数</font></h1><h2 id="1-函数的定义"><a href="#1-函数的定义" class="headerlink" title="1.函数的定义"></a><font size=3>1.函数的定义</font></h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line">[function] function_name() </span><br><span class="line">&#123;</span><br><span class="line">    list of commands.</span><br><span class="line">    [ return int_value ]</span><br><span class="line">&#125;</span><br></pre></td></tr></table></figure>

<p><strong>【注意】</strong></p>
<p>（1） function 是可选的，可以省略不写，直接就是函数名字也可以。</p>
<p>（2） return int_value 表示返回值，如果不加，将以最后一条命令运行结果，作为返回值。函数的返回值可以在调用该函数后通过 $? 来获得。</p>
<p>（3） Shell 中，通过 return 只能返回整数值，并且是 0-255 的范围，如果超出这个范围就会错误的结果。</p>
<p>（4）如果希望直接从终端调用函数，可以将函数定义在主目录下的  .profile  文件，这样每次登录后，在命令提示符后面输入函数名字就可以立即调用。</p>
<h2 id="2-函数的调用"><a href="#2-函数的调用" class="headerlink" title="2.函数的调用"></a><font size=3>2.函数的调用</font></h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">方式1</span></span><br><span class="line">function_name [arg1 arg2 ...]</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">方式2</span></span><br><span class="line">value_name= function_name  [arg1 arg2 ... ] </span><br></pre></td></tr></table></figure>

<p><strong>【注意】</strong></p>
<p>（1）函数必须先定义后使用，这意味着必须将<strong>函数放在脚本开始部分</strong>，直至 shell 解释器首次发现它时，才可以使用。不像 C 语言一样可以只在前边声明函数，到最后再定义。</p>
<p>（2） Shell 函数的调用只<strong>需要写出函数名</strong>即可，不需要写出括号 () 。</p>
<h2 id="3-函数的删除"><a href="#3-函数的删除" class="headerlink" title="3.函数的删除"></a><font size=3>3.函数的删除</font></h2><p>像删除变量一样，函数也可以被删除。</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">$</span><span class="language-bash"><span class="built_in">unset</span> .f function_name</span></span><br></pre></td></tr></table></figure>

<h2 id="4-函数的参数传递"><a href="#4-函数的参数传递" class="headerlink" title="4.函数的参数传递"></a><font size=3>4.函数的参数传递</font></h2><h3 id="4-1传参格式"><a href="#4-1传参格式" class="headerlink" title="4.1传参格式"></a><font size=3>4.1传参格式</font></h3><p>在 Shell 中，调用函数时可以向其传递参数。在函数体内部，通过  $n （也就是位置变量）的形式来获取参数的值。除了 $n 还有几个特殊字符也可以用于处理参数。</p>
<table>
    <tr>
        <td align="center" width=100px>${n}</td>
        <td align="left">位置变量</td>
    </tr>
    <tr>
        <td align="center" width=100px>${*}</td>
        <td align="left">以一个单字符串显示所有向脚本传递的参数</td>
    </tr>
    <tr>
        <td align="center" width=100px>${$}</td>
        <td align="left">脚本运行的当前进程ID号</td>
    </tr>
    <tr>
        <td align="center" width=100px>${!}</td>
        <td align="left">后台运行的最后一个进程的ID号</td>
    </tr>
    <tr>
        <td align="center" width=100px>${@}</td>
        <td align="left">与$*相同，但是使用时加引号，并在引号中返回每个参数</td>
    </tr>
    <tr>
        <td align="center" width=100px>${?}</td>
        <td align="left">显示最后命令的退出状态。0表示没有错误，其他任何值表明有错误</td>
    </tr>
    <tr>
        <td align="center" width=100px>$#</td>
        <td align="left">传递到脚本或函数的参数个数</td>
    </tr>
</table>

<p><strong>【注意】</strong> 最后一个  #  特殊字符在使用时也可以加  {} ，只不过这里不写是因为加上后，会导致 Hexo 渲染后的页面发生错乱。</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">定义函数时使用传入的参数</span></span><br><span class="line">[function] function_name() </span><br><span class="line">&#123;</span><br><span class="line">    echo &quot;$1&quot; # 输出第1个位置变量</span><br><span class="line">    echo &quot;$&#123;10&#125;&quot; # 输出第10个位置变量</span><br><span class="line">&#125;</span><br><span class="line"><span class="meta prompt_"></span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">调用函数时传入参数</span></span><br><span class="line">function_name [ arg1 arg2 arg3 ... ] </span><br></pre></td></tr></table></figure>

<h3 id="4-2使用实例"><a href="#4-2使用实例" class="headerlink" title="4.2使用实例"></a><font size=3>4.2使用实例</font></h3><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line">function test() </span><br><span class="line">&#123;</span><br><span class="line">    for var in 1 2 3 4 5 6 7 8 9 10</span><br><span class="line">    do</span><br><span class="line">        echo &#x27;$&#x27;$&#123;var&#125;&#x27; = &#x27;$&#123;var&#125;&#x27; &#x27;</span><br><span class="line">    done</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">test 10 9 8 7 6 5 4 3 2 1 0</span><br></pre></td></tr></table></figure>

<p>输出结果为：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">$</span><span class="language-bash">1 = 1</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">2 = 2</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">3 = 3</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">4 = 4</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">5 = 5</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">6 = 6</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">7 = 7</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">8 = 8</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">9 = 9</span> </span><br><span class="line"><span class="meta prompt_">$</span><span class="language-bash">10 = 10</span></span><br></pre></td></tr></table></figure>

<h2 id="5-函数内部的变量"><a href="#5-函数内部的变量" class="headerlink" title="5.函数内部的变量"></a><font size=3>5.函数内部的变量</font></h2><h3 id="5-1两种作用域"><a href="#5-1两种作用域" class="headerlink" title="5.1两种作用域"></a><font size=3>5.1两种作用域</font></h3><p> shell 函数内部可以定义变量，有两种定义方式。两种方式代表了变量有不同的作用域。</p>
<ul>
<li><p>全局作用域：在脚本的其他任何地方都能够访问该变量。</p>
</li>
<li><p>局部作用域：只能在声明变量的作用域内(函数内部)访问。</p>
</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">局部变量</span></span><br><span class="line">local variable_name=value</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">全局变量</span></span><br><span class="line">variable_name=value</span><br></pre></td></tr></table></figure>

<h3 id="5-2使用实例"><a href="#5-2使用实例" class="headerlink" title="5.2使用实例"></a><font size=3>5.2使用实例</font></h3><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line">function test() </span><br><span class="line">&#123;</span><br><span class="line">    var1=10</span><br><span class="line">    local var2=20</span><br><span class="line">    echo &quot;函数内打印在函数内部定义的变量&quot;</span><br><span class="line">    echo &quot;var1=$&#123;var1&#125;&quot;</span><br><span class="line">    echo &quot;var2=$&#123;var2&#125;&quot;</span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line">test</span><br><span class="line">echo &quot;函数外打印在函数内部定义的变量&quot;</span><br><span class="line">echo &quot;var1=$&#123;var1&#125;&quot;</span><br><span class="line">echo &quot;var2=$&#123;var2&#125;&quot;</span><br></pre></td></tr></table></figure>

<p>输出结果为：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br></pre></td><td class="code"><pre><span class="line">函数内打印在函数内部定义的变量</span><br><span class="line">var1=10</span><br><span class="line">var2=20</span><br><span class="line">函数外打印在函数内部定义的变量</span><br><span class="line">var1=10</span><br><span class="line">var2=</span><br></pre></td></tr></table></figure>

<p>可以看出，局部变量 var2 的值在函数外是访问不到的。</p>
<h1 id="二、文件包含"><a href="#二、文件包含" class="headerlink" title="二、文件包含"></a><font size=3>二、文件包含</font></h1><h2 id="1-使用格式"><a href="#1-使用格式" class="headerlink" title="1.使用格式"></a><font size=3>1.使用格式</font></h2><p>shell 脚本与 C 语言一样，可以包含外部文件， shell 可以将外部脚本的内容合并到当前脚本。这样可以很方便的封装一些公用的代码作为一个独立的文件以便于使用。shell  文件包含的语法格式有两种：</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_"># </span><span class="language-bash">语法格式1</span></span><br><span class="line">. file_name</span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">语法格式2</span></span><br><span class="line">source file_name</span><br></pre></td></tr></table></figure>

<p><strong>【注意】</strong>被包含的脚本文件不需要可执行权限，使用source命令和点号 . 是等价的，类似于C&#x2F;C++中的#include预处理指令，都是将指定的脚本内容拷贝至当前的脚本中，由一个shell进程来执行。</p>
<h2 id="2-使用实例"><a href="#2-使用实例" class="headerlink" title="2.使用实例"></a><font size=3>2.使用实例</font></h2><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">------------以下分隔开的是两个文件---------</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">引用其他文件内容的文件</span></span><br><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file1.sh</span></span><br><span class="line">var1=aaa</span><br><span class="line">var2=bbb</span><br><span class="line">export var1</span><br><span class="line">echo &quot;file2========start&quot;</span><br><span class="line">. file2.sh</span><br><span class="line">echo &quot;file2========end&quot;</span><br><span class="line">echo &quot;&quot;</span><br><span class="line">echo &quot;file1.sh:var1=$&#123;var1&#125;(file1.sh中定义,export)&quot;</span><br><span class="line">echo &quot;file1.sh:var2=$&#123;var2&#125;(file1.sh中定义)&quot;</span><br><span class="line">echo &quot;file1.sh:var=$&#123;var&#125;(file2.sh中定义)&quot;</span><br><span class="line"><span class="meta prompt_"></span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">--------------------------------------</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">变量定义文件</span></span><br><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file2.sh</span></span><br><span class="line">var=&quot;file1.sh&quot;</span><br><span class="line"></span><br><span class="line">echo &quot;file2.sh:var1=$&#123;var1&#125;(file1.sh中定义，export)&quot;</span><br><span class="line">echo &quot;file2.sh:var2=$&#123;var2&#125;(file1.sh中定义)&quot;</span><br><span class="line">echo &quot;file2.sh:var=$&#123;var&#125;(file2.sh中定义)&quot;</span><br></pre></td></tr></table></figure>

<p>我们输入 .&#x2F;file1.sh 执行脚本，输出结果如下</p>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line">hk@ubuntu-22-04:~/桌面/1sharedfiles/6temp/myubuntu$ ./file1.sh </span><br><span class="line">file2========start</span><br><span class="line">file2.sh:var1=aaa(file1.sh中定义，export)</span><br><span class="line">file2.sh:var2=bbb(file1.sh中定义)</span><br><span class="line">file2.sh:var=file2.sh(file2.sh中定义)</span><br><span class="line">file2========end</span><br><span class="line"></span><br><span class="line">file1.sh:var1=aaa(file1.sh中定义,export)</span><br><span class="line">file1.sh:var2=bbb(file1.sh中定义)</span><br><span class="line">file1.sh:var=file2.sh(file2.sh中定义)</span><br></pre></td></tr></table></figure>

<h1 id="三、子shell？"><a href="#三、子shell？" class="headerlink" title="三、子shell？"></a><font size=3>三、子shell？</font></h1><p>上边的文件包含会把另一个脚本的内容复制到此脚本中执行，就很类似于C语言中的 include，还有其他方法可以执行其他脚本吗？还有以下两种方式：</p>
<ul>
<li><strong>fork</strong>: 如果脚本有执行权限的话，path&#x2F;to&#x2F;foo.sh 。如果没有的话就这样：sh path&#x2F;to&#x2F;foo.sh。</li>
<li><strong>exec</strong>: exec path&#x2F;to&#x2F;foo.sh</li>
</ul>
<p>这两种有什么特点？与上边的source有什么不同？我们来看一看吧</p>
<h2 id="1-fork"><a href="#1-fork" class="headerlink" title="1. fork"></a><font size=3>1. fork</font></h2><h3 id="1-1-使用格式"><a href="#1-1-使用格式" class="headerlink" title="1.1 使用格式"></a><font size=3>1.1 使用格式</font></h3><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">path/to/foo.sh     # 有执行权限</span><br><span class="line">sh path/to/foo.sh  # 五执行权限</span><br></pre></td></tr></table></figure>

<p>执行方式：在主脚本中写所要调用脚本的路径，比如 &#x2F;home&#x2F;hk&#x2F;1sharedfiles&#x2F;6temp&#x2F;file1.sh</p>
<p>特点：</p>
<p>（1）运行主脚本运行的的终端会新开一个子shell来执行脚本first.sh；</p>
<p>（2）子shell执行的时候，父shell还在；</p>
<p>（3）子shell执行完毕后返回父shell，子shell会继承父shell的环境变量，但是子shell中的环境变量不会带回父shell</p>
<h3 id="1-2-使用实例"><a href="#1-2-使用实例" class="headerlink" title="1.2 使用实例"></a><font size=3>1.2 使用实例</font></h3><ul>
<li>主调shell脚本：file1.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file1.sh</span></span><br><span class="line"></span><br><span class="line">A=999</span><br><span class="line">echo &quot;before fork: PID for file1.sh = $$&quot;</span><br><span class="line">export A</span><br><span class="line">echo &quot;In file1.sh: variable file1_variable=$A&quot;</span><br><span class="line"></span><br><span class="line">echo -e &quot;==&gt;&gt;&gt; using fork start\n&quot;</span><br><span class="line">/home/hk/1sharedfiles/6temp/file2.sh</span><br><span class="line"></span><br><span class="line">echo &quot;after exec/source/fork: PID for file1.sh = $$&quot;</span><br><span class="line">echo -e &quot;In file1.sh: variable file1_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>被调shell脚本：file2.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file2.sh</span></span><br><span class="line"></span><br><span class="line">echo &quot;PID for file2.sh = $$&quot;</span><br><span class="line">echo &quot;In for file2.sh get variable file1_variable=$A from file1.sh&quot;</span><br><span class="line">A=111</span><br><span class="line">export A</span><br><span class="line">echo -e &quot;In for file2_variable.sh: variable for file2_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>执行结果如下</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">hk@ubuntu-22-04:~/1sharedfiles/6temp$ ./file1.sh </span><br><span class="line">before fork: PID for file1.sh = 6773</span><br><span class="line">In file1.sh: variable file1_variable=999</span><br><span class="line">==&gt;&gt;&gt; using fork start</span><br><span class="line"></span><br><span class="line">PID for file2.sh = 6774</span><br><span class="line">In for file2.sh get variable file1_variable=999 from file1.sh</span><br><span class="line">In for file2_variable.sh: variable for file2_variable=111</span><br><span class="line"></span><br><span class="line">after exec/source/fork: PID for file1.sh = 6773</span><br><span class="line">In file1.sh: variable file1_variable=999</span><br></pre></td></tr></table></figure>

<h2 id="2-exec"><a href="#2-exec" class="headerlink" title="2. exec"></a><font size=3>2. exec</font></h2><h3 id="2-1-使用格式"><a href="#2-1-使用格式" class="headerlink" title="2.1 使用格式"></a><font size=3>2.1 使用格式</font></h3><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">exec script_path</span><br></pre></td></tr></table></figure>

<p>执行方式：exec + 脚本路径</p>
<p>特点：</p>
<p>（1）运行主脚本时不会新开一个子shell来执行被调用脚本first.sh，被调用的脚本与主脚本在同一个Shell内执行，所以被调用的脚本中声明的变量和环境变量, 都可以在主脚本中进行获取和使用。</p>
<p>（2）使用exec调用一个新脚本以后, 父脚本中exec行之后的内容就不会再执行。</p>
<h3 id="2-2-使用实例"><a href="#2-2-使用实例" class="headerlink" title="2.2 使用实例"></a><font size=3>2.2 使用实例</font></h3><ul>
<li>主调shell脚本：file1.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file1.sh</span></span><br><span class="line"></span><br><span class="line">A=999</span><br><span class="line">echo &quot;before fork: PID for file1.sh = $$&quot;</span><br><span class="line">export A</span><br><span class="line">echo &quot;In file1.sh: variable file1_variable=$A&quot;</span><br><span class="line"></span><br><span class="line">echo -e &quot;==&gt;&gt;&gt; using fork start\n&quot;</span><br><span class="line">exec /home/hk/1sharedfiles/6temp/file2.sh</span><br><span class="line"></span><br><span class="line">echo &quot;after exec/source/fork: PID for file1.sh = $$&quot;</span><br><span class="line">echo -e &quot;In file1.sh: variable file1_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>被调shell脚本：file2.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file2.sh</span></span><br><span class="line"></span><br><span class="line">echo &quot;PID for file2.sh = $$&quot;</span><br><span class="line">echo &quot;In for file2.sh get variable file1_variable=$A from file1.sh&quot;</span><br><span class="line">A=111</span><br><span class="line">export A</span><br><span class="line">echo -e &quot;In for file2_variable.sh: variable for file2_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>执行结果如下</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">hk@ubuntu-22-04:~/1sharedfiles/6temp$ ./file1.sh </span><br><span class="line">before fork: PID for file1.sh = 6808</span><br><span class="line">In file1.sh: variable file1_variable=999</span><br><span class="line">==&gt;&gt;&gt; using fork start</span><br><span class="line"></span><br><span class="line">PID for file2.sh = 6808</span><br><span class="line">In for file2.sh get variable file1_variable=999 from file1.sh</span><br><span class="line">In for file2_variable.sh: variable for file2_variable=111</span><br></pre></td></tr></table></figure>

<h2 id="3-source"><a href="#3-source" class="headerlink" title="3. source"></a><font size=3>3. source</font></h2><p>与 <code>fork</code> 的区别是不新开一个子 <code>Shell</code> 来执行被调用的脚本，而是在同一个 <code>Shell</code> 中执行. 所以被调用的脚本中声明的变量和环境变量, 都可以在主脚本中进行获取和使用。</p>
<p>其实从命名上可以感知到其中的细微区别，下面通过两个脚本来体会三种调用方式的不同:</p>
<h3 id="3-1-使用格式"><a href="#3-1-使用格式" class="headerlink" title="3.1 使用格式"></a><font size=3>3.1 使用格式</font></h3><figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">source script_path</span><br><span class="line">. script_path</span><br></pre></td></tr></table></figure>

<p>执行方式：source（或者 . ） + 脚本路径</p>
<p>特点： </p>
<p>（1）同exec的特点（1）即运行主脚本时不会新开一个子shell来执行被调用脚本file2.sh，被调用的脚本与主脚本在同一个shell内执行。</p>
<p>（2）使用source调用一个新脚本以后, 主脚本中exec行之后的内容还会执行。</p>
<p>（3）被调用的脚本中声明的变量和环境变量, 都可以在主脚本中进行获取和使用。</p>
<h3 id="3-2-使用实例"><a href="#3-2-使用实例" class="headerlink" title="3.2 使用实例"></a><font size=3>3.2 使用实例</font></h3><ul>
<li>主调shell脚本：file1.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file1.sh</span></span><br><span class="line"></span><br><span class="line">A=999</span><br><span class="line">echo &quot;before fork: PID for file1.sh = $$&quot;</span><br><span class="line">export A</span><br><span class="line">echo &quot;In file1.sh: variable file1_variable=$A&quot;</span><br><span class="line"></span><br><span class="line">echo -e &quot;==&gt;&gt;&gt; using fork start\n&quot;</span><br><span class="line">. /home/hk/1sharedfiles/6temp/file2.sh</span><br><span class="line"></span><br><span class="line">echo &quot;after exec/source/fork: PID for file1.sh = $$&quot;</span><br><span class="line">echo -e &quot;In file1.sh: variable file1_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>被调shell脚本：file2.sh</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta prompt_">#</span><span class="language-bash">!/bin/bash</span></span><br><span class="line"><span class="meta prompt_"># </span><span class="language-bash">filename: file2.sh</span></span><br><span class="line"></span><br><span class="line">echo &quot;PID for file2.sh = $$&quot;</span><br><span class="line">echo &quot;In for file2.sh get variable file1_variable=$A from file1.sh&quot;</span><br><span class="line">A=111</span><br><span class="line">export A</span><br><span class="line">echo -e &quot;In for file2_variable.sh: variable for file2_variable=$A\n&quot;</span><br></pre></td></tr></table></figure>

<ul>
<li>执行结果如下</li>
</ul>
<figure class="highlight shell"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br></pre></td><td class="code"><pre><span class="line">hk@ubuntu-22-04:~/1sharedfiles/6temp$ ./file1.sh </span><br><span class="line">before fork: PID for file1.sh = 6840</span><br><span class="line">In file1.sh: variable file1_variable=999</span><br><span class="line">==&gt;&gt;&gt; using fork start</span><br><span class="line"></span><br><span class="line">PID for file2.sh = 6840</span><br><span class="line">In for file2.sh get variable file1_variable=999 from file1.sh</span><br><span class="line">In for file2_variable.sh: variable for file2_variable=111</span><br><span class="line"></span><br><span class="line">after exec/source/fork: PID for file1.sh = 6840</span><br><span class="line">In file1.sh: variable file1_variable=111</span><br></pre></td></tr></table></figure>


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